Ok this one is a bit odd. Every now and then the idle will be normal. MOST of the time (about 95% of the time now) the idle falls to about the bottom of the tach. It does idle, and it's not rough surprisingly, but it's way off. Other times it idles where it should be.

If it idles that low for TOO Long the engine eventually dies and then it's a pain to start. It'll be at it's worst in traffic. For instance this morning on the way to work it idled that way. If I give it NO gas and just let it idle it eventually dies no matter how much gas I start to blip at it and just quits on me. I can then hold down the accelerator, start the car and we're back in business like nothing happened, although it'll take a bit longer to start than usual (few more cranks).

Now, another strange thing, in the mornings when it's warming up, I could go inside, make a cup of coffee, make lunch, pay my mortgage, do a rain dance, do some jumping jacks, do a lap around the block, come back and it's idling just fine. It appears only do have the issue of dying on me after the engine is warm, that's when it gets "hard to start" again. But if you turn the car off by key and turn it on it'll start right up. Weird eh?

Cold high idle appears to be fine.

It's a bit odd. And again, I have no issues with it at speed she runs like a champ. Just this weird idle. I think if I can get this sorted out i'll be a happy camper.

Things I have done (and it's done this since I had the car) recently

- Valve Adjustment
- New plugs
- New wires
- New cap
- New rotor
- New points
- New harness
- Lots of new grounds
- Tested TPS
- New swear words LOL
- Set the timing as well (which is pretty much spot on)

It did this before i did all of these things, and sometimes is better than others, but most the time it's inconsistent and floating at the bottom of the tach. Not sure if the timing would have anything to do with it, I do not have a fancy meter to check the dwell and all those cool things. I do have a timing light that I used though.

Feelin' nutso.

(edit) here is a video. (click it and itll play)

I'll had this problem with two of my 914's. It was the vacuum sensor on one of my cars. After the sensor got hot it didn't work properly at idle. See if you can borrow one and swap it out for a test. I vacuum test all of mine before installing them. Most of them will not hold a vacuum because the metal diafram has cracked. Good Luck, Rayjay

Check all vacuum lines & connections too, & trigger points for FI as well.

Then move on to testing MPS, AAR, FPS, etc.

Also, if fuel pump is still in the engine bay & this is happening in hot weather only, then that may play into it due to vapor lock problems with the heat in the engine bay (which is why 75-76 had factory pump location in the front trunk area). A factory service bulletin for 70-74 914s in the later 70's had mechs. move it up under the steering rack cover on the underpan at the access hole from the tunnel where the fuel lines daylight - I don't have the bulletin but my 914 was changed in 78-79-ish.

All of this will of course entail further expanding your cuss-cabulary!

Rayjay!

My first thought was a fuel delivery problem. Could be a bad pump or even the voltage going to the pump. There is a filter sock at the bottom of the fuel tank. Very likely this is clogged. you will need to remove the tank to check this. I have had fuel pump problems lately because of the relay board. Mine has a defective fuse holder. This causes a poor supply to the pump relay (and other things). An easy way to help test this is to install a pressure gauge. Remove the line at the cold start valve and install a gauge there. Leave it there (Ty wrap it to something). Gauges are fairly cheap. I got mine at McMaster Carr (mcmaster.com). A 60 psi gauge is perfect. Mine is glycerin filled. Now you can monitor the pressure to help eliminate this as a problem.

You know, now that you mention it... the pump does make a weird whining noise like it goes from a small whining noise to a high pitched one and then it goes away. it never did that before, not till the fire.

however, i've tested the voltage and the volts and amperage are great and the resistance on the wires are fabulous.

the issue happened way before it "made that noise" it's been doing this since I got it. it's just that it's become worse.

The hot idle/heat soaked engine issue is a common problem for d-jet. The factory addressed this with a short spacer that goes in between the head sensor and the head. I'm not sure how effective it was. It didn't do crap for one of my cars. You can start by checking that head sensor out. There are a cold and hot resistence values. I think cold is 2000 ohm, hot 0. The factory also had a 270 ohm resistor to put between the sensor and the wire harness to trick the brain into think the motor was colder, so it put more fuel in. You can get something close to that at an electronics place and rig something tempoarily and see if that helps.

I am having the EXACT same problem! 75 2.0 D-jet. when i first got it, it was fast on the idle, set the timing, the the idle and it began to have the problem when i got under 1400 for idle- good cold, warms up then does this. I have heard every thing from aar, cold start valve, head temp sensor and MPS- i bought a rebuild MPS less than an year ago, only 500 miles later and always garaged, hard to believe it it that but could be?
What about TPS? any other suggestions? just going to be trial an error, i think.
Let us know what you figure out. - as will i
P.W.- 914 in S.C.

Don't forget to check the injector o-rings as well. Those get overlooked a lot, and can cause vacuum leaks. They are available at flaps in a kit.

Okay here's an odd tidbit I found out.

I drove it the other day and the idle stuck at just a hair over 1k. Stayed there, literally, the whole time.

I noticed during stop and go traffic if I barely let the clutch out (as if to go from a stop) and immediately push it back in, as the rpms dropped, they would raise back up to either a NORMAL idle, or this "super low idle".

Later on... they would raise back up. And again, if i could get the rpms to drop, it would raise back to normal or "too low". This makes me think I've got a sticky vacuum valve in there, would I be correct in assuming? Seems like it's sticking to me.